Kubernetes Ingress

This task describes how to configure Istio to expose a service outside of the service mesh cluster, using the Kubernetes Ingress Resource.

{{< tip >}} Using a Gateway, rather than Ingress, is recommended to make use of the full feature set that Istio offers, such as rich traffic management and security features. {{< /tip >}}

Before you begin

Follow the instructions in the Before you begin and Determining the ingress IP and ports sections of the Ingress Gateways task.

Configuring ingress using an Ingress resource

A Kubernetes Ingress Resources exposes HTTP and HTTPS routes from outside the cluster to services within the cluster.

Let's see how you can configure a Ingress on port 80 for HTTP traffic.

1. Create an Ingress resource and an IngressClass:

   {{< text bash >}} $ kubectl apply -f - <<EOF apiVersion: networking.k8s.io/v1 kind: IngressClass metadata: name: istio spec: controller: istio.io/ingress-controller

   apiVersion: networking.k8s.io/v1 kind: Ingress metadata: name: ingress spec: ingressClassName: istio rules:

   • host: httpbin.example.com http: paths:
     • path: /status pathType: Prefix backend: service: name: httpbin port: number: 8000 EOF {{< /text >}}

   The IngressClass resource identifies the Istio gateway controller to Kubernetes, and the ingressClassName: istio value instructs Kubernetes that the Istio gateway controller should handle the following Ingress.

   Older versions of the Ingress API used the kubernetes.io/ingress.class annotation, and while it still works, it has been deprecated in Kubernetes for some time.

2. Access the httpbin service using curl:

   {{< text bash >}} $ curl -s -I -HHost:httpbin.example.com "http://$INGRESS_HOST:$INGRESS_PORT/status/200" ... HTTP/1.1 200 OK ... server: istio-envoy ... {{< /text >}}

   Note that you use the -H flag to set the Host HTTP header to "httpbin.example.com". This is needed because the Ingress is configured to handle "httpbin.example.com", but in your test environment you have no DNS binding for that host and are simply sending your request to the ingress IP.

3. Access any other URL that has not been explicitly exposed. You should see an HTTP 404 error:

   {{< text bash >}} $ curl -s -I -HHost:httpbin.example.com "http://$INGRESS_HOST:$INGRESS_PORT/headers" HTTP/1.1 404 Not Found ... {{< /text >}}

Next Steps

TLS

Ingress supports specifying TLS settings. This is supported by Istio, but the referenced Secret must exist in the namespace of the istio-ingressgateway deployment (typically istio-system). cert-manager can be used to generate these certificates.

Specifying path type

By default, Istio will treat paths as exact matches, unless they end in /* or .*, in which case they will become prefix matches. Other regular expressions are not supported.

In Kubernetes 1.18, a new field, pathType, was added. This allows explicitly declaring a path as Exact or Prefix.

Cleanup

Delete the IngressClass and Ingress configurations, and shutdown the [httpbin]({{< github_tree >}}/samples/httpbin) service:

{{< text bash >}} $ kubectl delete ingress ingress $ kubectl delete ingressclass istio $ kubectl delete --ignore-not-found=true -f @samples/httpbin/httpbin.yaml@ {{< /text >}}